1. Field of the Invention
The present invention relates to a valve attached to a fuel tank, which is disposed in a fuel tank of vehicles, such as automobiles, and the like.
2. Description of the Related Art
In a fuel tank of an automobile, there is disposed a valve attached to the fuel tank, such as a liquid-fuel flowing-out inhibition valve, an inlet check valve, etc.
Among these valves attached to a fuel tank, the liquid-fuel flowing-out inhibition valve inhibits a liquid fuel from flowing out into a vaporized fuel circulation system. Namely, adjacent to a fuel tank of an automobile, there is disposed a vaporized fuel circulation system, which is referred to as an evaporator circuit. The evaporator circuit introduces a vaporized fuel from a fuel tank into an outside canister, and stores it by adsorbing it on an activated carbon, or the like, thereby inhibiting the increment of the internal pressure, which results from the increment of the vapor pressure, in the fuel tank. The canister is joined to an engine. Accordingly, the vaporized fuel is released from the activated carbon by the inlet negative pressure of the engine, and is mixed into an air-fuel mixture. Thus, the vaporized fluid is again used as a fuel.
In the evaporator circuit, an opening, which is referred to as an evaporator opening, is formed in the fuel tank. The evaporator opening is usually formed at the uppermost portion of the fuel tank in order to inhibit the fuel from flowing into the evaporator circuit. However, since the liquid surface of the fuel moves up and down, there might be a fear that the liquid fuel flows in into the evaporator opening. When the liquid fuel flows in and arrives at the canister, it adsorbs onto the activated carbon. Accordingly, there might arise a fear that the liquid fuel hinders the usual adsoprtion action of the activated carbon for the vaporized fuel.
Hence, a liquid-fuel flow-out inhibition valve has been disposed conventionally in the fuel tank in order to inhibit a liquid fuel from flowing out from the evaporator opening. For example, in FIG. 16, there is illustrated a cross-sectional view of a conventional liquid-fuel flow-out inhibition valve. The conventional liquid-fuel flowing-out inhibition valve comprises a cover 101 and a case 102. The cover 101 is formed on an upper portion of a fuel tank 100 integrally therewith. The case 102 is provided with an evaporator opening 103, which is formed through an upper portion of the case 102, and a floating valve 105, which is disposed in the case 102, and is engaged with an opening end of the cover 101 by an engagement claw 104. Note that the cover 101 communicates with an evaporator circuit that is not shown. Moreover, an O ring 106 is disposed in a space between an inner peripheral surface of the cover 101 and an outer peripheral surface of the case 102, and secures a liquid-proof ability.
Among the valves attached to a fuel tank, the inlet check valve inhibits a fuel and a vapor, held in a fuel tank, from flowing inversely when supplying a fuel. Namely, the fuel, which is supplied through a fuel supply opening, flows in into the fuel tank. At this moment, there might be a fear that the fuel and the fuel vapor, held in the fuel tank, flows inversely back to the fuel supply opening.
Hence, an inlet check valve has been interposed conventionally between a fuel filler pipe and a fuel tank in order to inhibit the fuel, and the like, from flowing inversely. For example, in FIG. 17, there is illustrated a cross-sectional view of an inlet valve set forth in Japanese Unexamined Patent Publication (KOKAI) No. 2,001-163,069. The inlet check valve 200 comprises a cylinder-shaped case 202, in which a valve body 201 is provided. An O ring 208 is fitted around an upstream-side outer peripheral surface of the case 202. Moreover, a fastening flange 209 is disposed on the outer peripheral surface. Then, an engagement claw 203 is formed at the peripheral edge of the fastening flange 209. While, a cylinder-shaped portion 206 is disposed on an outer wall of a fuel tank 205 protrudingly therefrom and integrally therewith. An engagement step 207 is disposed around an upstream-side outer peripheral surface of the cylinder-shaped portion 206. Then, the inlet check valve 200 is installed to the fuel tank 205 by engaging the engagement claw 203 of the case 202 with the engagement step 207 of the cylinder-shaped portion 206. Moreover, the O ring 208 contacts with an inner peripheral surface of the cylinder-shaped portion 206 elastically, thereby securing a sealing ability.
However, the above-described conventional liquid-fuel flow-out inhibition valve is associated with the following problems. First, since, the case and the cover is connected by the claw engagement, the connected portions merely scatter by the number of the claws on the case. Moreover, even when only one of the plurality of claws disengages, the swinging of the case might occur so that there might be a fear that the other claws disengage one after another successively. Moreover, the connected portions are usually immersed into the fuel. Accordingly, because of the swelling of the component members, there might arise a fear that the engagement claws are all the more likely to disengage. In view of these causes, it might be impossible to say that there might be no fear that the engagement claws disengage to come off the case from the cover.
Second, as described above, the liquid fuel flows out mainly from the evaporator opening. However, since the claw engagement is not good inherently in terms of the liquid-proof ability, there might arise a fear that the liquid fuel flows out through the space between the case and the cover. Accordingly, in the conventional liquid-fuel flow-out inhibition valve, the O ring is disposed in the space between the case and the cover, but is an extravagant component member. Namely, it is necessary to give a liquid-proof ability to the space between the case and the cover to a certain extent or more, but it is necessary to give an excessive liquid-proof ability thereto to such an extent that an O ring is disposed therein. When an O ring is provided in a liquid-fuel flow-out inhibition valve, the number of the component parts increases by the quantity. Moreover, a process for assembling the O ring is required, and consequently the manufacturing cost of the liquid-fuel flow-out inhibition valve goes up.
Here, in order to reduce the number of the component parts and in order to secure a liquid-proof ability to a certain extent or more, it is possible to think of the following arrangements. For instance, the cover and the case are connected by the claw engagement, but, in addition thereto, ribs and roots are disposed on the outer peripheral surface of the case and the inner peripheral surface of the cover, respectively, so that the space can be formed in a zigzagged manner between the case and the cover. However, the arrangements additionally require manufacturing steps for processing the outer peripheral surface of the case and the inner peripheral surface of the cover, and consequently the manufacturing cost increases. In addition, because of the complexity of the configurations, the arrangements cannot be applied to small-sized liquid-fuel flow-out inhibition valve.
While, in the conventional inlet check valve, the case and the fuel tank are bonded by the claw engagement similarly to the above-described conventional liquid-fuel flow-out inhibition valve. As a result, the conventional inlet check valve might have a problem that it is inferior in terms of the bondability. Moreover, the O ring is disposed in the space between the case and the fuel tank. Thus, the conventional inlet check valve suffers from a problem that the number of component parts is large. Namely, the conventional inlet check valve is associated with problems similar to those of the conventional liquid-fuel flow-out inhibition valve.
The present invention has been completed in view of the aforementioned problems. It is therefore an object of the present invention to provide a valve attached to a fuel tank, valve which is favorable in terms of the bondability, which can secure a liquid-proof ability to a certain extent or more, whose construction is simple, and whose number of component parts is less.
In order to achieve the aforementioned object, a valve attached to a fuel tank according to a first aspect of the present invention permits a vaporized fuel to flow out, inhibits a liquid fuel from flowing out, and comprises: a cover bonded to an upper portion of a fuel tank, being independent of the fuel tank, and including a connecting surface to be connected to the fuel tank, the connecting surface having a connector portion formed of a resin exhibiting a good bondability to the fuel tank, and a flow-out passage in which a vaporized fuel flows out; and a case screwed to the cover, and including an evaporator opening, communicating with the flow-out passage, and a floating valve for opening or closing the evaporator opening.
Namely, in the valve attached to the fuel tank according to the first aspect of the present invention, the cover and the case are bonded by screw (i.e., fastening by thread), not by claw engagement. Since the connection exists in a helical manner continuously, the case and the cover are less likely to disengage than the case where they are connected by claw engagement. Thus, when the component parts swell, there is no fear that the case comes off from the cover. Further, since the space between the male screw and the female screw is extremely small, it is possible to secure a liquid-proof ability without disposing a sealing member, such as an O ring, etc., between the cover and the case. Specifically, while securing a liquid-proof ability to a certain extent or more, it is possible to reduce the number of component parts. Furthermore, it is possible to freely attach the case to and detach it from the cover by screw fastening. Accordingly, it is very convenient, for instance, when inspecting, replacing, and so on, the floating valve, disposed in the case.
Moreover, in the valve attached to the fuel tank according to the first aspect of the present invention, the fuel tank and the cover are bonded by the connector portion, which is disposed in the cover. Hence, even when the fuel tank and the cover are formed of materials, which exhibit poor bondabilites to each other, it is possible to properly secure a liquid-proof ability, because the cover is bonded to the connector portion, which is disposed on the fuel-tank connecting surface and which is formed of a resin exhibiting a good bondability, in other words, because the specific connector portion is interposed between the cover and the fuel tank.
In order to furthermore achieve the aforementioned object, a valve attached to a fuel tank according to a second aspect of the present invention modifies the valve according to the first aspect of the present invention so that the cover has a first screwed portion, the case has a second screwed portion, and a sealing member is further interposed between the first screwed portion and the second screwed portion.
Namely, in the valve attached to the fuel tank according to the second aspect of the present invention, the sealing member is interposed between the male screw and the female screw of the portions, which are screwed together. Between the male screw and the female screw, there is formed a helix-shaped fine space. In the valve attached to the fuel tank according to the second aspect of the present invention, the sealing member is interposed between the male screw and the female screw to bury the fine space.
By the valve attached to the fuel tank according to the second aspect of the present invention, it is possible to furthermore improve a liquid-proof ability at the screwed portions (i.e., the connection between the cover and the case).
In order to furthermore achieve the aforementioned object, a valve attached to a fuel tank according to a third aspect of the present invention modifies the valve according to the first aspect of the present invention so that the cover has a case-contacting surface, which contacts with the case in the axial direction, the case has a cover-contacting surface, which faces the case-contacting surface, one of the case-contacting surface and the cover-contacting surface has a ring-shaped groove, and the other one thereof has a ring-shaped rib, which faces the ring-shaped groove; and a leading end of the ring-shaped rib is pressed against an inner wall of the ring-shaped groove by screwing the case to the cover.
Namely, in the valve attached to the fuel tank according to the third aspect of the present invention, the ring-shaped groove is disposed in one of the case-contacting surface and the cover-contacting surface, and the ring-shaped rib is disposed on the other one thereof. To put it concretely, when the ring-shaped groove is disposed in the case-contacting surface, the ring-shaped rib is disposed on the cover-contacting surface. On the other hand, when the ring-shaped rib is disposed on the case-contacting surface, the ring-shaped groove is disposed in the cover-contacting surface.
By the valve attached to the fuel tank according to the third aspect of the present invention, it is possible to furthermore improve a liquid-proof ability by contacting the leading end of the ring-shaped rib with the inner wall of the ring-shaped groove.
In order to furthermore achieve the aforementioned object, a valve attached to a fuel tank according to a fourth aspect of the present invention modifies the valve according to the first aspect of the present invention so that the cover has a case-contacting surface, which contacts with the case in the axial direction, the case has a cover-contacting surface, which faces the case-contacting surface, and an elastic member, which urges the cover and the case in directions separating the case-contacting surface and the cover-contacting surface away from each other, is further interposed between the case-contacting surface and the cover-contacting surface.
Namely, in the valve attached to the fuel tank according to the fourth aspect of the present invention, the elastic member, which urges the cover-contacting surface and the case-contacting surface in directions away from each other, is interposed between the cover-contacting surface and the case-contacting surface, which approach each other in the axial directions when the case is screwed to the cover. As described above, a helix-shaped fine space is formed between the male screw and female screw of the screwed portions. However, since the urging force of the elastic member is transmitted to the screwed portions, the side surfaces of the male screw and the side surfaces of the screwed groove, which neighbor with each other, are pressed and contacted with each other. For example, the upper side surfaces of the male screw and the upper side walls of the female screw are pressed to contact with each other.
By the valve attached to the fuel tank according to the fourth aspect of the present invention, it is possible to enhance a liquid-proof ability by pressing the side surfaces of the male screw and the side walls of the female screw to contact with each other.
In order to achieve the aforementioned object, a valve attached to a fuel tank according to a fifth aspect of the present invention comprises: a cover bonded to a fuel tank, being independent of the fuel tank, and including a connecting surface to be connected to the fuel tank, the connecting surface having a connector portion formed of a resin exhibiting a good bondability to the fuel tank; and a case bonded to the cover.
Namely, in the valve attached to the fuel tank according to the fifth aspect of the present invention, the reduction of component parts is intended by bonding the cover and the case while securing a liquid-proof ability to a certain extent or more. When the cover and the case are bonded together, it is easy to secure a liquid-proof ability. As described above, it is not necessary inherently to give a liquid-proof ability to the space between the case and the cover by bonding. However, in the valve attached to the fuel tank according to the fifth aspect of the present invention, the liquid-proof ability can be secured without disposing a sealing member, and the like, additionally. Consequently, it is possible to achieve the intended object (i.e., to reduce the number of component parts).
Therefore, in the valve attached to the fuel tank according to the fifth aspect of the present invention, when a flow-out passage, in which a vaporized fuel flows out, is disposed in the cover, and when an evaporator opening, which communicates with the flow-out passage, and a floating valve, which opens or closes the evaporator opening, are disposed in the cover, it is possible to secure a liquid-proof ability between the flow-out passage and the evaporator opening while reducing the number of component parts. Note that, when the case is welded to the cover, the liquid-proof ability is furthermore improved.
Moreover, in the valve attached to the fuel tank according to the fifth aspect of the present invention, when a flow-in passage, into which a supplied fuel flows in, is disposed in the cover, and when a valve body, which demarcates the flow-in passage and the fuel tank openably or closeably, is disposed in the case, it is possible to secure a liquid-proof ability between the flow-in passage and the fuel tank while reducing the number of component parts. Note that, when the case is welded to the cover, the liquid-proof ability is furthermore improved.
In order to achieve the aforementioned object, a valve attached to a fuel tank according to a sixth aspect of the present invention permits a vaporized fuel to flow out, inhibits a liquid fuel from flowing out, and comprises: a cover bonded to an upper portion of a fuel tank, being independent of the fuel tank, and including a connecting surface to be connected to the fuel tank, the connecting surface having a connector portion formed of a resin exhibiting a good bondability to the fuel tank, and a flow-out passage in which a vaporized fuel flows out; a case connected to the cover by claw engagement, and including an evaporator opening, communicating with the flow-out passage, and a floating valve for opening or closing the evaporator opening; the cover having a first surface; the case having a second surface neighboring the first surface; and an elastic lip erected on at least one of the first surface and the second surface and having a leading end contacted elastically with the other one of the first surface and the second surface.
Namely, in the valve attached to the fuel tank according to the sixth aspect of the present invention, the cover and the case are connected by claw engagement. Moreover, in order to inhibit the deterioration of the liquid-proof ability resulting from the above-described claw engagement, the elastic lip is erected on at least one of the first surface of the case and the second surface of the cover, and has the leading end contacted with the other one of the first surface and the second surface. The elastic lip can be formed as a ring-shaped film, etc. For instance, when the elastic lip is erected on the second surface of the case, the leading end of the elastic lip is contacted elastically with the first surface of the cover to secure a liquid-proof ability.
By the valve attached to the fuel tank according to the sixth aspect of the present invention, not only it is possible to connect the case and the cover by claw engagement with relative readiness, but also it is possible to secure a liquid-proof ability by the elastic lip.
In order to achieve the aforementioned object, a valve attached to a fuel tank according to a seventh aspect of the present invention permits a vaporized fuel to flow out, inhibits a liquid fuel from flowing out, and comprises: a cover bonded to an upper portion of a fuel tank, being independent of the fuel tank, and including a connecting surface to be connected to the fuel tank, the connecting surface having a connector portion formed of a resin exhibiting a good bondability to the fuel tank, and a flow-out passage in which a vaporized fuel flows out; and a case connected to the cover, and including an evaporator opening, communicating with the flow-out passage, and a floating valve for opening or closing the evaporator opening; wherein the cover and the case are connected by pressing-in and one of the cover and the case, to be pressed in into the other one thereof, has an outer peripheral surface, on which a flange portion, having a triangle-shaped cross section tapering from wide to narrow in the pressing-in direction, is formed.
Namely, in the valve attached to the fuel tank according to the seventh aspect of the present invention, the cover and the case are connected by pressing-in. On an outer peripheral surface of one of the cover and the case (i.e., the pressed-in member), the flange portion is formed which has a triangle-shaped cross section. Moreover, the flange portion is tapered gradually from wide to narrow in the pressing-in direction. Therefore, it is possible to press in the pressed-in member into the press-in receiving member with a relatively small press-in load. It is possible to secure a liquid-proof ability between the pressed-in member and the press-in receiving member by pressing the top surface of the flange portion to contact with an inner peripheral surface of the press-in receiving member. On the other hand, when pulling out the pressed-in member from the press-in receiving member, a relatively large pull-out load is needed because the flange portion acts like a wedge. Thus, when the pressed-in member is once pressed in into the press-in receiving member, the pressed-in member is less likely to fall off from the press-in receiving member.
By the valve attached to the fuel tank according to the seventh aspect of the present invention, it is possible to connect the case and the cover by the simple pressed-in arrangement with relative readiness. In addition, by the pressing-and-contacting action of the top surface of the flange portion, it is possible to secure a liquid-proof ability without employing a sealing member, such as an O ring, and the like.
In order to achieve the aforementioned object, a valve attached to a fuel tank according to an eighth aspect of the present invention permits a vaporized fuel to flow out, inhibits a liquid fuel from flowing out, and comprises: a cover bonded to an upper portion of a fuel tank, being independent of the fuel tank, and including a connecting surface to be connected to the fuel tank, the connecting surface having a connector portion formed of a resin exhibiting a good bondability to the fuel tank, and a flow-out passage in which a vaporized fuel flows out; and a case connected to the cover by claw engagement, and including an evaporator opening, communicating with the flow-out passage, and a floating valve for opening or closing the evaporator opening; wherein the case has a press-in portion to be pressed in into said cover and the press-in portion has an outer peripheral surface, on which a flange portion, having a triangle-shaped cross section tapering from wide to narrow in the pressing-in direction, is formed.
Namely, in the valve attached to the fuel tank according to the eighth aspect of the present invention, the cover and the case are connected by claw engagement. Moreover, in order to inhibit the deterioration of the liquid-proof ability resulting from the above-described claw engagement, the flange portion is formed on the outer peripheral surface of the press-in portion.
By the valve attached to the fuel tank according to the eighth aspect of the present invention, not only it is possible to connect the case and the cover by claw engagement with relative readiness, but also it is possible to secure a liquid-proof ability by the flange portion.
In order to furthermore achieve the aforementioned object, a valve attached to a fuel tank according a ninth aspect of the present invention modifies either one of the above-described valves attached to the fuel tank so that the connector portion of the cover is formed of an adhesive polyethylene, portions of the cover excepting the connector portion are formed of a polyamide, the case is formed of a reinforced polyamide, and the fuel tank is formed of a polyethylene.
Namely, in the valve attached to the fuel tank according to the ninth aspect of the present invention, the portions of the cover excepting the connector portion and the case are formed of the same kind of polyamide resins.
Because of the following reasons, the case is formed of a reinforced polyamide, and the portions of the cover excepting the connector portion are formed of a polyamide. Namely, since the case is placed in a manner immersed into a liquid fuel, there may be a fear that the case swells. When the case swells, as set forth above, there may arise a fear that the case falls off from the cover. In order to suppress the swelling, a reinforcement member, such as glass fibers, etc., is dispersed in a matrix composed of a polyamide. Thus, the case is upgraded in terms of the anti-swelling property.
While, regarding the cover, the issue is the fuel permeability. For instance, when the cover is formed of a material, such as a polyethylene, etc., the resulting cover exhibits a large fuel permeation. Taking the gradually strengthened evaporation regulation into consideration, it is necessary to make the cover from a material, which exhibits a fuel permeation as little as possible. A polyamide, which is used herein as a matrix of the case, exhibits a fuel permeation less. Consequently, a polyamide is an appropriate material for forming the case. Note that, since the cover is not placed in a liquid fuel, it is not necessary to take the anti-swelling property into account, and accordingly it is not required to reinforce a polyamide for making the case with glass fibers, and the like. Moreover, the cover might be subjected to mechanical shocks because of vibrations, and so on, which are transmitted from the other instruments, and the like, boarded on an automobile, etc. Note that, however, the cover might be degraded in terms of the shock resistance when it is formed of a polyamide reinforced with glass fibers, and so. Accordingly, the cover is formed of a not-reinforced polyamide.
Due to the aforementioned reasons, the case is formed of a reinforced polyamide, and the cover is formed of a not-reinforced polyamide.
Here, the cover is formed of a polyamide, there arises an issue of the bondability to a fuel tank. Namely, in many cases, a fuel tank, made from a resin, is formed of a polyethylene. However, the polyethylene and the polyamide exhibit extremely poor bondabilities to each other. Hence, the inventors of the present invention designed to dispose the connector portion, which is made from an adhesive polyethylene, in the connecting surface of the cover to be connected to the fuel tank. An adhesive polyethylene has functional groups, which bond to amide groups of a polyamide by denaturation with maleic anhydride, etc., in its side chains. Therefore, it is possible to weld the connector portion, formed of an adhesive polyethylene, to the cover, formed of a polyamide, by injection molding, and to weld the cover to a fuel tank, formed of a polyethylene, by hot-plate welding, respectively, for example. Note that the hot-plate welding is a method in which a heated steel plate is applied onto a surface of a component part to soften and thereafter the other resinous component part is applied onto the surface to weld the component parts with each other.
In accordance with the ninth aspect of the present invention, in the resulting valve attached to the fuel tank, it is possible to reduce the number of component parts. Moreover, it is possible to upgrade the anti-swelling property as well as the shock resistance.
In order to achieve the aforementioned object, a valve attached to a fuel tank according to a tenth aspect of the present invention comprises: a cover bonded to a fuel tank, being independent of the fuel tank, and including a connecting surface to be connected to the fuel tank, the connecting surface having a connector portion formed of a resin exhibiting a good bondability to the fuel tank, and a flow-in passage into which a supplied fuel flows in; and a case connected to the cover, and including a valve body demarcating the flow-in passage and the fuel tank openably or closeably; wherein the cover and the case are connected by pressing-in and one of the cover and the case, to be pressed in into the other one thereof, has an outer peripheral surface, on which a flange portion, having a triangle-shaped cross section tapering from wide to narrow in the pressing-in direction, is formed.
Namely, in the valve attached to the fuel tank according to the tenth aspect of the present invention, the cover and the case are connected by pressing-in. On an outer peripheral surface of one of the cover and the case (i.e., the pressed-in member), the flange portion is formed.
By the valve attached to the fuel tank according to the tenth aspect of the present invention, it is possible to connect the case and the cover by pressing-in with relative readiness. In addition, it is possible to secure a liquid-proof ability by the flange portion.
In accordance with the present invention, it is possible to provide a valve attached to a fuel tank, in which the bondability is good between a cover and a case, in which the liquid-proof ability is secured to a certain extent or more, whose construction is simple and whose number of component parts is less. In addition, it is possible to provide a valve attached to a fuel tank, valve which is good in terms of the anti-swelling property and the shock resistance.